PROPERTY AND EQUIPMENT (Details) (USD $) Share data in Thousands, unless otherwise specified	1 Months Ended	3 Months Ended				9 Months Ended				1 Months Ended
	Feb. 29, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Divestiture East Texas	Oct. 29, 2012 Subsequent Event Divestiture East Texas mi	Oct. 29, 2012 Subsequent Event Divestiture Louisiana
Property, Plant and Equipment [Abstract]
General and administrative costs (including stock-based compensation) capitalized to oil and gas properties from continuing operations		$ 9,300,000			$ 15,800,000	$ 29,600,000	$ 37,900,000
Interest costs capitalized to unproved oil and gas properties from continuing operations		1,690,000			3,044,000	5,787,000	7,509,000
Impairment of unproved properties in South Africa		66,900,000
Discount factor used in full cost ceiling test (as a percent)						10.00%
Ceiling test write-down of oil and natural gas properties		329,957,000	349,000,000	34,800,000	0	713,750,000	0
Acquisitions
Common stock issued for acquisition of unproved oil and natural gas properties (in shares)	2,657
Common stock issued for acquisition of unproved oil and natural gas properties	36,431,000					36,431,000	0
Divestitures
Proceeds from sale of oil and natural gas assets and properties		7,800,000				8,800,000				34,000,000	220,000,000
Amount of additional performance payments contingent on future activity										9,000,000
Length of gas gathering agreement (in years)										10 years
Miles from current configuration of gathering system that Company has committed production from existing and future operated wells under the gas gathering agreement (in miles)										5
Assets held for sale		27,373,000				27,373,000		0	27,373,000
Impairment charge on assets held for sale									$ 12,700,000